My take on everything that happened in AoU is that AoU stands for A Other Universe because the whole thing was balls from start to finish. The only bit worth putting on screen was Steve moving Mjolnir and Steve tearing that log in half. That film could have been 20 seconds long and it would have been better than the garbage Joss Whedon shat out.
I pretty much agree with this. That said, I would like to point out that those hallucinations were supposed to be the characters’ worst fears – i.e. Tony sees a situation where all his friends are dead and it’s his fault, Thor sees his kingdom destroyed. Now I think this was just inconsistent storytelling and we were supposed to think that Steve’s vision was tempting him, even though other characters were shown frightening things.
However, the fact remains that what we are show canonically implies that Steve’s worst fear was coming home at the end of the war and dancing with Peggy. I think that’s particularly interesting because this movie takes place after WS, when Steve is actively looking for Bucky, so he knows that if he hadn’t been there Bucky probably never would’ve been able to break his programming. And in the dream Bucky is conspicuously absent. Basically he sees a life without Bucky, a future where he didn’t go down with the plane, where he turned his back on him.
Personally I think Steve put that plane in the water and made no attempt to escape it because he didn’t want to live in a world without Bucky. His worst fear seems to be the idea that in some alternate universe he didn’t make that choice.